[texhax] little table within table cell

[Geoffrey Knauth]

I have a table in plain TeX that looks like this:

-- Sat Sun Mon ...
MA   0   1   2 ...

I want it to look like this:

-- Sat Sun Mon ...
    5/27 5/28 5/29
MA   0   1   2 ...

Where Sat / 5/27 are within one cell, Sat appearing above 5/27.

I did this:

\valign{\strut#&#\cr Sat&5/27\cr}

but then Sat / 5/27 took up nearly the entire width of the page.   
What did I do wrong?

Thanks,
Geoffrey
--
Geoffrey S. Knauth | http://knauth.org/gsk